Efficient Use of Natural Gas Based Fuels in Heavy-Duty Engines
DEER Conference Fuels and High-Performance Lubricants
October 19, 2012
Clean Automotive Technology www.epa.gov/otaq/technology
John J. Kargul Director of Technology Transfer
National Center for Advanced Technology
Office of Transportation and Air Quality U.S. Environmental Protection Agency
Why Natural Gas as a Transportation Fuel?
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Reducing Oil Imports via US Natural Gas Opposing the “Triple Threat” to the U.S. • Preserving Economic Stability
– Retaining capital in US economy, creating jobs – Investing in US energy infrastructure
• Guarding National Security – Avoid subsidizing oil imports through our military budget – Protecting domestic ownership of US infrastructure
• Protecting the Environment – Meeting our energy needs while ensuring alternatives
achieve national emissions and GHG goals
Using domestic NG resources is critical to meeting these challenges!
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Domestic Alternative Fuel Pathways
Gasoline • Conventional • MTG
Diesel • Conventional • Fischer-Tropsch
Biodiesel Ethanol Methanol CNG / LNG Electricity Hydrogen
Conventional Flex-fuel Dedicated fuel Dual-Fuel
• Alcohol • CNG
EV/PHEV Fuel cell
Feedstocks Fuels
Vehicles
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Petroleum • Conventional • Unconventional • Tight shale oil
Natural Gas • Conventional • Shale Gas
Biomass • Woody • Herbaceous • Corn/sugar • Fats/oils • Wind/solar/renewables
Coal • Oil shale (kerogen)
EPA’s Alcohol Engine Research Programs
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Hot Surface Ignition
Spark Ignition
Dual-Fuel
Waste Heat Recovery
Compression Ignition (cetane additives)
Spark Ignition
Dedicated Fuel
Engines
Flex-Fuel Engines
1980 1990 2000 2010 Clean Automotive Technology www.epa.gov/otaq/technology
Technology Simple upgrade to diesel engine:
• Retain diesel fuel system • Retain diesel EGR system • Add 2nd fuel tank for alcohol fuel (ethanol or methanol) • Add port fuel injection system for alcohol fuel • Revisions to engine ECU • DPF may be necessary
No NOx aftertreatment necessary
Around 5% more efficient than today’s diesel engines
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Dual-Fuel Engine
Diesel-Methanol (M100) Calibrated to 0.27 g/kWh NOx
Brake Efficiency (%) Particulate Emissions (FSN)
40%
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.02 to .08
Results from EPA’s initial engine calibration
Dual-Fuel Engine
Diesel-Methanol (M100) M100 Substitution Ratio (mass basis)
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85% • Results are from initial engine dyno calibration • We have also seen
results with 90% peak efficiency • With a better fuel
injection strategy the substitution ratio would increase during lower power operation
Dual-Fuel Engine
Diesel-Methanol versus CNG Estimated Fuel Economy
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CNG Diesel-Methanol 5.1 mpg (class 8) 7.0 mpg* (class 6)
6.3 mpg (class 8) 8.4 mpg* (class 6)
Uses gasoline-engine technology
• Throttled, spark ignition • Around 15% less efficient
than today’s diesel
Uses diesel engine technology
• No throttle, compression ignition • No SCR fuel penalty • Around 5% more efficient than
today’s diesel engines
Baseline diesel: 8.0 mpg (class 6), 6.0 mpg(class 8) *Assumes a typical EPA City cycle, which favors dual-fuel approach (no throttling, better idle fuel economy)
Dual-Fuel Engine
Regional variation in retail fuel prices (July 2012) Diesel Gallon Equivalent (DGE) basis
West Coast CNG=$2.50 Diesel =$3.92
Rocky Mountain CNG=$1.90 Diesel =$3.66
Gulf Coast CNG=$2.32 Diesel =$3.64
New England CNG=$2.77 Diesel=$3.84
Central Atlantic CNG=$2.47 Diesel =$3.80
Lower Atlantic CNG=$1.91 Diesel =$3.67
Midwest CNG=$2.09 Diesel =$3.70
National Average
CNG=$2.28 Diesel=$3.75
Source: July 2012 DOE Clean Cities Alternative Fuel Price Report
Tulsa, OK: CNG=$1.50
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Estimating Operating Costs
Global price variability: Unsustainable Differences
“The solution to low prices is… low prices.”
concluding remark at EIA workshop August 23, 2012
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Estimating Operating Costs
Natural Gas vs. Crude Oil Price
Source: EIA
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X
• Historic price relationship between NG and Crude would suggest that the commodity price of NG should be around $10 / MMBTU
• Expect NG prices to eventually return to historic relationship as demand for NG increases As coal electric power
plants are converted to NG, and As the LNG export
market comes on-line With balanced
production versus demand relationship
(Common Energy Basis)
Estimating Operating Costs
Dual Fuel Methanol-Diesel versus LNG Cost of Vehicle Operation versus Years of Ownership: Class 8 Truck
Projected 2017 price levels (based on EIA’s 2012 AEO Report)
Projected 2017 price levels (based on historic NG price levels)
(Assumes 50 vehicles, 200k miles per year; historic NG pricing for 2017 yields NG commodity prices at $9.26/MMBTU)
(Assumes 50 vehicles, 200k miles per year; EIA projection for 2017 yield NG commodity prices at 4.76/MMBTU)
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LNG LNG
Diesel-M100 Diesel-M100
Diesel-E100 Diesel baseline
Estimating Operating Costs
Dual Fuel Methanol-Diesel versus CNG Cost of Vehicle Operation versus Years of Ownership: Class 6 Delivery Truck
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(Assumes 50 vehicles, 20k miles per yr; EIA projection for 2017 yields NG commodity prices at $4.76/MMBTU)
(Assumes 50 vehicles, 20k miles per yr; historic NG pricing for 2017 yields NG commodity prices at $9.26/MMBTU)
Clean Automotive Technology www.epa.gov/otaq/technology
Projected 2017 price levels (based on EIA’s 2012 AEO Report)
Projected 2017 price levels (based on historic NG price levels)
Diesel baseline
CNG fast fill
CNG slow fill
CNG no station
Estimating Operating Costs
Highlights
• Simple adaptation of a conventional diesel • No SCR needed • 5% more efficient that conventional diesel • No engine performance degradation • Fuel costs are 20-30% less that for all diesel • Modest cost for methanol fueling equipment • Deployment can easily begin with centrally
fueled fleets
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Dual-Fuel Engine
Next Development Steps Vehicle Demonstrations
– Class 6 UPS truck evaluation – Fall 2012 – Potential for a pilot program of 10-20 class 6 & 8 vehicles
Continued refinement of dual-fuel technology – Refine engine calibration and engine fuel injection system
to maximize methanol consumption • Optimize engine control strategy for transient performance
– Optimize turbomachinery, fuel injection systems, combustion chamber, EGR system, etc.
– Extend application to less-expensive fuels (e.g., “crude” M100)
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Dual-Fuel Engine
Thank You
The remaining slides contain reference information about EPA’s
dual-fuel engine.
17 Clean Automotive Technology www.epa.gov/otaq/technology
Dedicated Alcohol Spark Ignition Engine (calibrated for M85)
Diesel-like efficiency at a cost similar to a turbocharged gasoline engine
Potential cold start,
durability issues —engineering solutions exist
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40%
Efficiency
Engine Platforms for EPA’s Alcohol Research Dedicated M85 Spark Ignition Dual Fuel (Diesel/M100)
Base Engine Test Platform Navistar VT-275 Navistar 4.8L Configuration 6 cyl, 60-degree V 4 cyl, inline Displacement 4.5 liters 4.8 liters Bore x Stroke 95mm x 105mm 105mm x 137mm
Compression Ratio 16.3:1 (base diesel = 18:1) 16.8:1
Max. power 140 kW @ 2200 rpm 143 kW @ 2200 rpm Valvetrain 4 valve/cyl, overhead valve 4 valve/cyl, overhead valve
Fuel Injectors PFI, 2 per cyl PFI (2/cyl); HPCR/1800 bar Fuel Type M85 M100/Diesel
Ignition System Spark Ignition (CDI) (None) Air Induction System Twin VGT VGT
Engine Control Module Pre-production controller Pre-production controller Exhaust Aftertreatment Three-way catalyst DOC
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Dedicated M85 Spark Ignition Dual Fuel (Diesel-M100)
Refueling Transparent to user Special refueling procedures
Cold starting Fuel additives or charge air heating Diesel: glow plug
Oil dilution High Moderate Fuel - alcohol content/
quality tolerance Moderate/fair High
Limp home capability De-rated operating range with lower octane fuels
Diesel only operation, limited range
Bottoming cycle compatibility
Cold starting requires10-15% gasoline, reducing possibility for effective exhaust heat reforming
M100 as primary fuel, suitable for exhaust
heat reforming
Comparison of General Features
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Dedicated M85 Spark Ignition Dual Fuel (Diesel-M100)
Refueling Transparent to user Special refueling procedures
Cold starting Fuel additives or charge air heating Diesel: glow plug
Oil dilution High Moderate Fuel - alcohol content/
quality tolerance Moderate/fair High
Limp home capability De-rated operating range with lower octane fuels
Diesel only operation, limited range
Bottoming cycle compatibility
Cold starting requires10-15% gasoline, reducing possibility for effective exhaust heat reforming
M100 as primary fuel, suitable for exhaust
heat reforming
Comparison of General Features
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Dedicated M85 Spark Ignition Dual Fuel (Diesel-M100)
Cylinder Head Modified for spark plug No change from stock
Combustion Chamber Pistons modified for lower CR No change from stock
Intake Manifold Modified for port fuel injectors (PFI)
Modified for port fuel injectors (PFI)
Fuel system 4 bar PFI or 150 bar DI 4 bar PFI and 2000 bar DI
Ignition type High-energy SI No change from stock
Aftertreatment TWC DOC
EGR system LP cooled EGR Dual loop cooled EGR
Air induction system Single-stage VGT with high-capacity aftercooler No change from stock
Engine Hardware Comparison
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Dedicated M85 Spark Ignition Dual Fuel (Diesel-M100)
Maximum load 18-20 bar BMEP 16-18 bar BMEP EGR levels up to 20% up to 40-50% Max. boost
requirement 2 bar-abs 2.4 bar-abs
Peak cylinder pressures 130 bar 180 bar
MRPR (bar/deg) 3-5 bar/deg 10-12 bar/deg
Engine Combustion Comparison
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CNG Diesel-Methanol Hardware added: • Spark ignition system • CNG gaseous fuel injection
system • CNG storage tanks and
related equipment (125 mi range)
Hardware added: • Diesel fuel injection system • Methanol-compatible fuel
system and tank • DOC/DPF in place of TWC • Turbo • Cooled EGR system
Estimated add-on cost is $18,000 - $20,000 more than a gasoline-powered class 6 truck*
Estimated add-on cost is $6,000 more than a gasoline-powered class 6 truck*
Dual-Fuel Diesel-Methanol vs. CNG Vehicle Costs*
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* A diesel engine for a class 6 truck is estimated at $14,000 higher than gasoline.
CNG “Fast Fill” LNG Methanol • Gaseous fuel, 3600 psi • Training required
•Cryogenic liquid, 3600 psi • Training required
• Liquid fuel, conventional filling nozzle
• Minimal training required for safe handling and dispensing
• High heat gain during fast fueling results in 30+% loss of vehicle range
• High heat gain during fast fueling results in 30+% loss of vehicle range
• n/a
• Industrial utility services o 8 inch NG service o Electrical demand
• High capital cost (>$2M)
• Industrial utility services o 8 inch NG service o Electrical demand
• High capital cost (>$2M)
• In-ground or above-ground tanks
• Modest cost ($30-$55k)
Comparison of Natural Gas-Based Fuels Methanol vs. CNG/LNG
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26 Clean Automotive Technology www.epa.gov/otaq/technology
Dual-Fuel Engine Team National Vehicle & Fuel Emissions Laboratory U. S. Environmental Protection Agency • Matthew J. Brusstar • Allen B. Duncan • Michael Prince • Charles L. Gray, Jr.
